GT Course 853 - Rust Repair
11-04-10, 04:48 PM
#1
Junior Member
Thread Starter
Join Date: Jul 2010
Location: Florida's Space Coast
Posts: 11
Bikes: n/a
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
GT Course 853 - Rust Repair
A friend of mine picked up a GT Course 853 road bike (1998?). This bike came with an Ultegra set. I think this was a TIG welded frame and has severe rusting at the stays-to-top tube connection and also some pitting/rusting at the tube intersections with the bottom bracket. It is in otherwise clean condition. Here's an example, I can provide others:
He is riding the bike and he is not shall we say, dainty.
Is this frame toast or can something be done? I was thinking perhaps a frame strip and a bead blasting followed by silver brazing the pitted (holed?) tubing but I don't know. The rusting seems to be localized to the welded areas which makes me wonder about some deficiency in the welding process.
He is riding the bike and he is not shall we say, dainty.
Is this frame toast or can something be done? I was thinking perhaps a frame strip and a bead blasting followed by silver brazing the pitted (holed?) tubing but I don't know. The rusting seems to be localized to the welded areas which makes me wonder about some deficiency in the welding process.
11-04-10, 07:14 PM
#2
Randomhead
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 24,396
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,696 Times
in
2,517 Posts
it just has to do with the paint not adhering as well at the joints for all sorts of reasons. No problem with the welds. I really don't know what you can do, but I would probably try an oxalic acid bath first.
11-05-10, 01:27 AM
#3
THE Materials Oracle
Join Date: Feb 2006
Location: Finally... home :-)
Posts: 502
Bikes: Univega Alpina 5.1 that became a 5.9, that became a road bike... DMR TrailStar custom build
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
NO!
NO!
NO!
NO!
Never, *ever* acid pickling on steels over 1300MPa strength, unless you'd like to crack the remaining steel through in a few hours. No strong acids over 1000MPa, and no weak acids or alkalis over 1300Mpa. Hydrogen embrittlement, man!
You want to get that rust off safely? Blackstrap molasses dissolved to 10% in hot water. Find a nice big vessel, large enough to drop the whole frame in, and then leave it to soak for a couple of days.
But make sure you've washed any grease or dirt off first :-)
NO!
NO!
NO!
Never, *ever* acid pickling on steels over 1300MPa strength, unless you'd like to crack the remaining steel through in a few hours. No strong acids over 1000MPa, and no weak acids or alkalis over 1300Mpa. Hydrogen embrittlement, man!
You want to get that rust off safely? Blackstrap molasses dissolved to 10% in hot water. Find a nice big vessel, large enough to drop the whole frame in, and then leave it to soak for a couple of days.
But make sure you've washed any grease or dirt off first :-)
Thread
Thread Starter
Forum
Replies
Last Post
Buikema
Classic & Vintage
44
06-13-10 10:34 PM
